There is a flu outbreak at your school that starts with 10 people. The number of ill students increases by 20% each hour. Write an exponential function to represent the total number of ill students, f(x), where x is the number of hours after the outbreak.

a. f(x) = 10(1.2)^x

b. f(x) = 1.2(10)^x

c. f(x) = 10(.20)^x

d. None of the above